S_N2′ reaction of organozinc reagents activated by catalytic tBu-P4 base in the presence of LiCl

The tBu-P4 base was found to be an excellent catalyst for the activation of organozinc reagents. The base was used to promote the S_N2′ reaction of α,β-unsaturated esters bearing a γ-chloride in the reactions with various organozinc reagents in the presence of LiCl. The reactions proceeded in high yield with excellent chemo-and regioselectivity. The role of LiCl appears to be the activation of the y-chloride of the α,β-unsaturated esters, which was confirmed by NMR spectroscopic study.